Vehicle bed edge manufacturing process

ABSTRACT

A vehicle bed assembly, and process of manufacture, which involves formation of a one-piece floor pan by roll forming. The floor pan has a central pan portion and secondary portions positioned forwardly and rearwardly of wheelwell openings formed in the pan adjacent opposite side edges thereof. Strengthening ribs extend longitudinally throughout the entire length of the pan and terminate at the front and rear edges. The strengthening ribs also extend longitudinally of the secondary portions and terminate at front and rear edges of the wheelwell openings. The one-piece floor pan has the wheelwell openings formed therein, as by a controlled notching operation, after the pan has been roll formed from flat sheet material, and the notching operation provides a series of flanges around the periphery of the wheelwell opening, both along the longitudinal inner edge and on the front and rear edges. Some of the flanges are coplanar with top walls of the stiffening ribs, and others are coplanar with the base wall of the pan between the stiffening ribs. The roll-formed pan is subjected to a subsequent forming operation which causes the flanges to be wiped downwardly generally into a perpendicular relationship so that the flanges are positionable in overlapping relationship to the vehicle inner side wall or wheelwell housing for securement thereto, such as by welding.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional of Ser. No. 09/196,979, filed Nov. 20, 1998 now abandoned, which is a continuation-in-part of application Ser. No. 08/903,887 filed Jul. 31, 1997, now U.S. Pat. No. which in turn is a continuation-in-part of 6,128,815, application Ser. No. 08/780,834 filed Jan. 10, 1997, now U.S. Pat. No. 5,938,272.

FIELD OF THE INVENTION

This invention relates to an improved one-piece ribbed floor pan for a vehicle bed, such as a truck bed, and the related process of manufacture.

BACKGROUND OF THE INVENTION

A box of a vehicle, such as a pickup truck, is illustrated in FIG. 1. This box conventionally includes a horizontally enlarged floor or bed assembly 12 which extends sidewardly between and is joined to generally parallel and upwardly extending side panels or walls 13. The side panels 13 conventionally have wheelwell housings 14 formed therein, the latter typically projecting at least inwardly a small extent into the interior of the box. The front end of the floor assembly 12 is also rigidly joined to an upwardly-projecting front wall or panel 15, the latter extending between and being rigidly fixed to the side panels 13. The rear of the box is normally closed by a rear-panel 16, the latter conventionally being an openable tailgate 16 which is conventionally hingedly joined to the box and can swing into an open generally horizontal position wherein it is substantially flush with the floor assembly to provide access to the interior of the box.

This box, and specifically the floor or bed assembly 12, conventionally includes a horizontally enlarged main bed member 17, commonly referred to as the floor pan, which defines the actual floor of the box and extends lengthwise between the front and rear ends of the box, and has a width which normally substantially spans the width of the opening between the wheelwell housings. This main floor pan 17 is supported on a front cross rail 18, several intermediate cross rails 19, and a rear cross rail or sill member 21, the latter all extending transversely under the pan and being fixedly secured thereto, such as by spot welding. Some of these cross members, such as the front rail 18, the frontmost intermediate rail 19 and the rear sill 21 are typically fixedly secured to the vehicle frame (not shown) in a conventional manner.

The bed assembly 12 also normally includes secondary bed or floor pan members 22, the latter being positioned adjacent and fixedly joined to opposite longitudinal edges of the main floor pan 17 so as to occupy the regions of the bed disposed forwardly and rearwardly of the wheelwell housings 14.

In the pickup box as conventionally constructed, the main floor pan 17 is provided with stiffening ribs 23 which project upwardly from the pan, with a plurality of such ribs being generally uniformly sidewardly spaced apart across the width of the pan and extending longitudinally of the pan over a majority of the length thereof. These ribs, which are deformed upwardly from the pan to define a downwardly-opening channel-like cross section, generally extend rearwardly from adjacent the front free edge of the main pan 17 but the ribs normally terminate in tapered rib ends 24 which merge downwardly into the planar profile of the pan 17 at a location disposed close to but spaced forwardly a small distance from the rear free edge 25 of the pan. The rear edge portion of the main pan 17, namely the flat portion thereof which is free of the ribs, is then normally seated within a shallow recess formed in the top wall of the rear sill member 21 so as to be substantially flush with the upper surface of the sill member, with the rear pan and sill member then being suitably fixedly secured together, such as by spot welding. This arrangement enables the groovelike regions defined between adjacent ribs 23 to freely open outwardly through the rear end of the bed assembly, and hence prevent creation of pockets or recesses which would collect dirt or moisture. The secondary pan members 22 also conventionally have stiffening ribs 23 formed therein and extending longitudinally of the bed, with the stiffening ribs 23 in the secondary pan members 22 again typically terminating short of the front and rear edges of the respective pan member.

FIG. 2 illustrates therein another conventional prior art box of a vehicle, such as a pickup truck, wherein the parts thereof corresponding to FIG. 1 have been identified by the same reference numerals but with the addition of a prime (′) thereto. The bed assembly 12′ of FIG. 2 again includes an enlarged main bed member or portion 17′ which extends longitudinally throughout the length of the bed and defines the region which extends generally transversely between the wheelwell housings of the vehicle. The bed assembly 12′ also again includes secondary bed members or portions 22′ which occupy the regions of the bed disposed forwardly and rearwardly of the wheelwell housings 14. In this prior art construction, however, the main bed portion 17′ and the secondary portions 22′ are all integrally formed in one piece and, as is generally conventional, are provided with downwardly depending flanges which project generally longitudinally along the side edges and also along the edge of the wheelwell openings for permitting securement to the adjacent side panels or wheelwell housings. The stiffening ribs associated with both the main and secondary portions 17′ and 22′, respectively, again are formed such that the ends thereof terminate in longitudinally spaced relation from the longitudinal end edges, particularly the rear edge of the bed.

A bed assembly having the structure described above has, for a very long time, been constructed using individual members which have been stamped utilizing large forming presses. That is, the floor pan 17 (FIG. 1) or 17′, 22′ (FIG. 2) as well as the cross rails 18, 19 and 21 have been conventionally formed from flat steel sheets by positioning a precut steel sheet in a forming press which deforms the sheet to define the desired cross section of the finished member. This stamping or press-forming technique, however, even though extensively utilized for many years, possesses recognized disadvantages which have nevertheless been long tolerated in view of the belief that this was the best manner of constructing the bed assembly.

More specifically, the current and almost universally utilized technique of stamping the pan has resulted in limitations which have restricted optimum construction of the pan. For example, to stamp the floor pan 17 of FIG. 1, a large rectangular sheet must be precut in accordance with the size of the desired pan being stamped. The sheet is initially of excess width so as to provide portions along opposite edges of the sheet which can be used for clamping the sheet and holding it in position when the sheet is positioned within the press and subjected to the stamping operation. Further, during the actual stamping operation, the material of the sheet is physically deformed by the stamping die so as to permit creation of the longitudinal ribs. This necessarily results in significant changes in thickness of the sheet material due to the deformation which is caused during the rib formation process. Not only does the sheet undergo significant changes in thickness, but this change in thickness is also of varying amounts at different locations across the rib, or through the cross section of the sheet containing the ribs, so that the resulting stamped floor pan has a sheet thickness which has significant variation therein. This thickness variation can in some instances be as much as 40% to 50%. This stamping process has also been observed to result in bends or corners which are inconsistent in terms of both material thickness and included angle, and have provided a finished exterior appearance which permits such irregularities to be visually observed. This stamping operation also requires, after the pan has been stamped, that the pan be subjected to a further stamping or cutting operation which is effective for removing the clamping strip portions on opposite sides of the sheet, which strip portions are disposed of as scrap.

In view of the inherent but inconsistent thickness reductions which occur during forming of the pan by the stamping or pressing process, the pan must also be initially formed from a sheet material of greater thickness than desired so as to compensate for the expected thickness reductions which occur during the stamping operation. This increases the overall weight of the pan. Further, in view of the significant size of the main floor pan and the fact that it is deformed or stamped in basically a single pressing operation, this also necessitates utilization of an extremely large and high capacity forming press in order to accommodate both the size of the sheet and the significant pressing force encountered during the simultaneous deformation of the numerous ribs which extend longitudinally thereof. Further, these stamping operations necessarily can normally be successfully carried out only if lower strength and softer sheet steels are utilized since harder strength steels will typically split or crack if subjected to severe deformation of the type encountered in the conventional pan stamping operation.

The floor pan 17′, 22′ of FIG. 2 is basically formed in the same manner described above relative to the floor pan 17 of FIG. 1 in that it is typically formed by stamping in a large press from a single large precut rectangular sheet, which precut sheet also has the wheelwell openings precut in the sides thereof prior to stamping of the sheet in the forming press. This pan 17′, 22′, however, obviously experiences the same problems and deficiencies which result from this type of forming operation as described above.

In addition, when the pan of FIG. 2 is formed in a press, the securing flanges along the side edges and around the wheelwell are also press formed, either simultaneous with the overall pressing of the ribbed pan or in a subsequent pressing operation. In this pressing operation, the flanges are bent downwardly, and this has been observed to create manufacturing disadvantages in both the finished product and in the assembly thereof to the vehicle. For example, during this downward bending, the flange is basically swung in a cantilevered fashion about its hinge connection to the main pan member, and this results in undesired weakening due to thinning of the sheet material directly at the hinge point, and possible cracking. Further, since the flange typically extends substantially continuously along and around the wheelwell opening, the flange also tends to buckle at various points, and this causes undesired distortions in the flange. Even more-significantly, this bending of the flange makes it difficult to position the flange accurately in downwardly perpendicular relation to the sheet, and in fact there is a well observed and known tendency for the flange to spring back when the bending force is removed, thereby making it difficult to achieve the desired accuracy of perpendicularly of the flange with respect to the sheet. This lack of accurate perpendicularly consequently often makes it difficult for the flanges to be properly fit against and be welded to a wheelwell housing.

To improve on the above-described vehicle bed structure and forming method thereof, the Assignee of this application developed the improved truck bed structures and forming methods disclosed in U.S. Pat. Nos. 5,188,418, 5,544,932, 5,575,525, and 5,730,486, all of which are assigned to Pullman Industries, Inc., the Assignee hereof, and all of which are herein incorporated by reference.

In the aforesaid patents, a truck bed is disclosed including a floor pan having strengthening ribs constructed by a roll-forming process. A rear sill member cooperates with the rear edge of the floor pan and preferably has upward protrusions which interfit within and generally close the rearward ends of the ribs formed in the pan, whereby the ribs are capable of extending to the rear free edge of the pan and open longitudinally outwardly thereof to permit roll forming of the pan while facilitating proper water drainage from the bed when the pan is assembled in the vehicle, with the rear edge of the pan and specifically the ribs thus being supported and reinforced by the rear sill and the protrusions thereon.

In a continuing effort to improve on the truck bed disclosed in the aforementioned patents, the aforementioned '486 patent additionally discloses that the rear free edge of the ribbed roll-formed floor pan can be formed with a reinforcing flange extending longitudinally along the rear free edge, which flange projects downwardly so as to effectively overlap rear surfaces defined on the protrusions and rear sill to thus provide additional reinforcement directly at the rear free edge of the pan or bed.

The improved roll-formed bed arrangement as briefly summarized above, and specifically as disclosed in the aforementioned patents, was developed primarily to permit forming of a bed assembly in a manner similar to that illustrated in FIG. 1. That is, the roll-formed bed member disclosed in the aforementioned patents was intended primarily to be the main central pan member equivalent to the main pan member 17 of FIG. 1, whereby separate secondary pan members equivalent to the secondary pan members 22 of FIG. 1 would then be used in conjunction with the main pan member, which secondary members could be formed either by roll forming or by stamping. Manufacture of the main pan member 17 by roll forming, as disclosed in the aforementioned patents, was believed to be the most satisfactory approach for using roll forming in association with a vehicle bed so as to minimize and avoid unnecessary subsequent forming operations, such as stamping operations, which were considered to be of questionable feasibility if such forming operations had to be carried out subsequent to the roll forming of the ribbed pan member. While the aforementioned patents broadly suggest roll forming of the main and secondary pans as an integral one-piece member and the subsequent processing thereof to create wheelwell openings, nevertheless the aforementioned patents do not teach how such could be accomplished and, in view of the additional difficulties presented by this proposal, significant additional development and design is and was required in order to go beyond the broad suggestion of these patents.

Accordingly, it is an object of this invention to provide an improved vehicle bed assembly, specifically a truck bed assembly, and a method of manufacturing and assembling the primary components of the truck bed assembly, so as to overcome many of the disadvantages associated with the conventional and long-utilized stamp bed assemblies as described above, and so as to also provide further improvements over the roll-formed bed assemblies disclosed in the Assignee's aforementioned patents.

More specifically, the present invention relates to an improved vehicle bed assembly, and process of manufacture, which involves formation of a one-piece floor pan by roll forming, which floor pan has a main central pan portion as well as secondary or wing portions which are positionable forwardly and rearwardly of wheelwell openings formed in the pan adjacent opposite side edges thereof. The floor pan has strengthening ribs which extend longitudinally throughout the entire length thereof so as to terminate at the front and rear edges. The strengthening ribs extend in parallel relationship longitudinally throughout not only the main pan portion, but also longitudinally of the secondary portions, whereby these ribs terminate directly at front and rear edges of the wheelwell openings. The one-piece floor pan has the wheelwell openings formed therein, as by a controlled notching or punching operation, after the pan has been roll formed from flat sheet material, and the notching operation provides a series of flanges around the periphery of the wheelwell opening, both along the longitudinal inner edge and also on the front and rear edges thereof. The flanges are disposed in spaced relation, with some of the flanges being coplanar with top walls of the stiffening ribs, and others being coplanar with the bottom or base wall of the pan between the stiffening ribs. The roll-formed pan is subjected to a subsequent forming operation which causes the flanges to be wiped downwardly generally into a transverse or perpendicular relationship with respect to the plane of the base wall of the pan so that the flanges are positionable in adjacent and overlapping relationship to the truck inner side wall or wheelwell housing for securement thereof, such as by welding. The roll-formed ribs extend longitudinally of the pan and thus terminate not only at the rear free edge thereof, but also at the front and rear edges of the wheelwell openings.

In the preferred construction of the invention, as briefly summarized above, the rear of the one-piece pan is positioned on a rear support sill or channel member which extends transversely of the vehicle adjacent the rear of the bed. This sill preferably incorporates upper protrusions in spaced relationship therealong, which protrusions project upwardly into the rearward free ends of the stiffening ribs to support and reinforce the stiffening ribs directly adjacent the rearward free ends thereof.

The improved pan or bed member, as aforesaid, preferably provides the stiffening ribs in uniformly sidewardly-spaced relationship transversely across the main pan portion, with the ribs preferably having top walls of substantial transverse width to define the direct load-bearing surface of the bed assembly. The sidewardly spacing between adjacent ribs is typically selected so that the spacing, as defined by the base wall of the pan, is generally no greater than and preferably less than the transverse width of the top wall of the stiffening ribs to maximize the upper surface area defined by the top walls of the ribs. The configuration of the pan member and specifically the roll-formed rib pattern therein, however, is preferably selected so that the longitudinally-extending inner edge of the wheelwell is formed in a base wall as defined between two sidewardly adjacent ribs. Further, the base wall containing the longitudinally-extending inner edge of the wheelwell is, in a preferred embodiment, provided with a greater transverse width than the base walls between the other ribs so as to facilitate the creation of a flange along the longitudinally inner edge of the wheelwell, which flange can initially be formed from and coplanar with the base wall, and then subsequently deformed downwardly in generally perpendicular relationship therewith to facilitate the overall forming of the pan.

In the improved bed assembly of this invention, as aforesaid, the one-piece bed member is also preferably provided with at least two downwardly-projecting cantilevered securing flanges integrally associated with each of the front and rear edges of each wheelwell opening. These two cantilevered flanges are disposed in sidewardly-spaced relation and are of different lengths, with a longer one of the flanges being integral with the top wall of a stiffening rib which intersects the wheelwell opening, and the other flange being of shorter extent and integral with a base wall which intersects the wheelwell opening. These flanges when deformed downwardly both terminate at about the same elevation and permit securement to the vehicle, such as direct securement to the wheelwell housing.

The present invention also relates to an improved process for forming the vehicle bed, as aforesaid, specifically a one-piece roll-formed ribbed bed member having wheelwell openings formed in opposite side thereof, as well as the process for securing the bed member to the support rails and rear sill as well as other vehicle components to effectively define an assembled bed assembly.

The present invention, in addition to the improvements and advantages briefly summarized above, is also believed to provide manufacturing economies with respect to the overall manufacturing process, and permit creation of cross sections or shapes in the bed and specifically in the pan member which are not possible with stamping or press-forming operations, including the creation of sharper corners having a higher consistency with respect to both curvature and thickness.

The present invention also contemplates providing on the improved bed or pan member a modified rear edge construction which includes a generally flat and planar flange which defines the rear free edge of the bed member, and which is created by deforming, i.e., flattening, the raised ribs throughout a small longitudinal distance forwardly away from the rear free edge of the bed member. This flat and substantially planar flange can then be positioned to substantially directly overlie one of the surfaces of the rear sill. In one variation of this modification, the flange is bent downwardly to overlie a rear surface of the rear sill, whereas in another variation of this modification the flange is disposed so as to lie directly on the upper surface of the rear sill.

The present invention also includes as a modification of the rear edge construction of the bed member the forming of the ribs, directly adjacent the rear end of the bed member, with downwardly sloped configurations so that the ribs effectively taper downwardly from their maximum height to the lower base wall height as they project rearwardly, whereby the ribs effectively reduce to substantially zero height at or substantially at the rear edge of the bed member while still providing continuous longitudinally extending channels between the ribs which permit unrestricted drainage of water from the vehicle bed. The tapered rib portions at the rear ends of the ribs are preferably defined by being physically compressed or deformed, as by a pressing die, so as to cause a gradual decrease in the height of the ribs over a small longitudinal distance in the direct vicinity of the rear edge of the bed member. These tapered rib end portions can be disposed so as to either define the actual free rear edge of the bed member, or can be disposed just forwardly of and monolithically joined to a flat rear flange, as described above, so as to constitute a transition between the rear flange and the lengthwise-extending ribs of uniform height.

The processing of the roll-formed bed member to include a flat rear edge flange and/or tapered rear rib portions, as described above, can be accomplished using the same basic process for forming and making the roll-formed bed member in that the deforming of the ribs into a downward slope or taper, and the deforming of the rear rib portions into a flat flange, can be accomplished at the same workstations utilized for carrying out other forming operations on the bed member which has already been roll formed and cut to length, such as when the bed member is in the stations utilized from piercing and punching, or for deforming the securing flanges.

Other objects and purposes of the invention will be apparent to persons familiar with structures and processes of this general type upon reading the following specification and inspecting the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a conventional pickup truck box which illustrates a first well know construction of a bed assembly.

FIG. 2 is a top plan view similar to FIG. 1 but illustrating a second well known construction of the bed assembly.

FIG. 3 is an exploded perspective view illustrating the basic components which cooperate with the improved pan member of this invention so as to define the improved bed assembly of this invention.

FIG. 4 is a perspective view which illustrates the improved one-piece floor pan according to the present invention.

FIG. 5 is an enlarged fragmentary perspective view of a portion of FIG. 4 and specifically illustrating that part of a one-piece pan member having a wheelwell opening formed therein.

FIG. 6 is a fragmentary top view of one side portion of the one-piece pan member subsequent to roll forming thereof, but prior to notching of the wheelwell opening therein.

FIG. 7 is a fragmentary sectional view taken generally along line 7—7 in FIG. 6.

FIG. 7A is an enlarged fragmentary sectional view similar to FIG. 7 but illustrating the preferred corrugated cross sectional configuration of the pan achieved by roll forming of the pan according to the present invention.

FIG. 8 is a fragmentary top view corresponding to FIG. 6 but showing the pan member subsequent to a notching operation which simultaneously effects formation of the wheelwell opening as well as formation of securing tabs at locations along the periphery of the wheelwell opening.

FIG. 9 is a fragmentary top view corresponding to FIG. 8 but showing the one-piece pan member subsequent to a wiping operation which causes the securing tabs both along the side edge of the pan and the side edge of the wheelwell opening to be deformed downwardly for deposition substantially as illustrated by FIG. 5.

FIG. 10 is an exploded, fragmentary perspective view showing the rear of the pan member and its relationship to the rear sill.

FIG. 11 is a enlarged fragmentary sectional view illustrating upper and lower punch members used for effecting notching of the wheelwell opening in the roll-formed pan member as illustrated in FIG. 8, the cross section of the lower support member being taken generally along line 11—11 in FIG. 12.

FIG. 12 is a perspective view illustrating the lower support member used in notching the wheelwell opening.

FIGS. 13A, 13B and 13C are fragmentary sectional views which illustrate the process for forming the attachment or securing flanges associated with edges of the roll-formed pan of this invention, with

FIG. 13A showing the flange following the roll forming thereof and prior to forming of the flange,

FIG. 13B showing the flange in a partially formed position, and

FIG. 13C showing the flange in its fully formed position.

FIG. 14 is an elevational view, partially in cross section, which diagrammatically illustrates the flange forming arrangement for effecting drawing of an edge flange on the bed member consistent with the forming sequence illustrated by FIGS. 13A through 13C.

FIGS. 15A and 15B are enlarged, fragmentary sectional views showing the flanges as formed on the respective rear and front edges of the bed member.

FIG. 16 is a top plan view showing one-half of the bed member following the treatment thereof at the notching and piercing station, it being recognized that the bed member is generally symmetrical about the longitudinal central axis thereof.

FIG. 17 is a diagram which diagrammatically illustrates the forming equipment and process used for forming of the bed member and the subsequent securement thereof to the cross rails.

FIG. 18 is a flow process chart which describes the primary processing sequence associated with forming of the bed member and subsequent attachment of rails thereto.

FIGS. 19 and 20 are charts which expand the process steps of FIG. 18.

FIG. 21 is an enlarged, fragmentary sectional view showing a modified rear edge construction for the roll-formed bed member and showing its position on a transversely-extending rear sill.

FIG. 22 is a fragmentary sectional view taken generally along line 22—22 in FIG. 21.

FIG. 23 is a view similar to FIG. 21 but illustrating a further modification of the rear edge construction of the bed member and its positioning on a rear sill.

FIG. 24 diagrammatically illustrates, in a separated condition, a first re-strike die used for deforming the rear edge portion of the roll-formed bed member so as to create the rear edge construction illustrated by FIGS. 21 and 23.

FIG. 25 is a fragmentary section view taken generally along line 25—25 in FIG. 24.

FIG. 26 diagrammatically illustrates, in separated condition, a second re-strike die used subsequent to the application of the first die of FIGS. 24-25 so as to complete formation of the rear edge construction illustrated in FIG. 23.

FIG. 27 is a fragmentary sectional view taken generally along line 27—27 in FIG. 26.

FIG. 28 diagrammatically illustrates, in separated condition, a modified second re-strike die used subsequent to application of the first re-strike die of FIGS. 24-25 so as to permit formation of the rear edge construction shown by FIG. 21.

Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The word “upwardly” will also be used in reference to an exposed top surface of the floor pan of the bed assembly. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the box or bed assembly, or designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.

DETAILED DESCRIPTION

The improved vehicle bed assembly of the present invention will now be described, particularly with reference to FIGS. 3-9.

The floor or bed assembly 30 of the invention, as illustrated specifically by FIGS. 3 and 4, employs a main floor pan or bed member 31 which cooperates with and has the rear edge thereof supported on a rear cross rail or sill member 32, the latter extending transversely across the vehicle bed adjacent the rear end thereof. The pan or bed member 31 is also supported adjacent the front edge thereof on a front cross member or rail 33, and several (three in the illustrated embodiment) intermediate cross rails 34 are also fixedly secured under the bed member 31 in parallel but spaced relation between the front and rear cross rails. This general arrangement is conventional.

The floor pan or bed member 31 is formed, preferably roll formed as described hereinafter, from a thin sheet 35 of metal, preferably high strength steel having a thickness of about 0.8 mm, so that the pan member 31 is of an integral and monolithic one-piece construction with the pan member having substantially uniform thickness throughout the entire transverse and longitudinally cross sectional extent thereof.

The one-piece monolithic pan member 31, following its being longitudinally roll formed and cut to length, is of a generally horizontally enlarged rectangular configuration and has front and rear free edges 36 and 37, respectively, extending transversely of the longitudinally-extending (i.e., front to back) direction of the pan member. The pan member additionally has generally parallel side edges 38 which extend longitudinally and substantially perpendicularly intersect the respective front and rear free edges.

The rectangularly-shaped roll-formed pan member 31, as generally described above, has a pair of wheelwell openings 41 formed therein subsequent to the roll forming of the pan member. The wheelwell openings 41 are typically disposed intermediate the front and rear edges of the pan member, and open inwardly from the respective side edges 38 so that the pair of wheelwell openings are transversely aligned relative to the longitudinal direction of the bed member. Each wheelwell opening 41 has a configuration so as to receive therein the wheelwell housing 14 associated with the respective vehicle side wall 13. The wheelwell opening 41, as illustrated in FIGS. 4 and 9, has an inner edge 42 which is elongated generally longitudinally of the bed member and which joins to respective front and rear edges 43 and 44 which project transversely outwardly and intersect the side edge 38 of the bed member. The front and rear edges 43 and 44 are joined to the inner edge 42 through arcuate or rounded edges or corners 45. The exact shape of the wheelwell opening 41 will, of course, vary depending upon the overall vehicle construction, but will generally have a configuration similar to that described above.

The monolithic one-piece bed member 31, when the wheelwell openings 41 are formed therein, thus includes a main central bed section 47 which extends longitudinally between the respective front and rear edges 36 and 37, and also extends transversely between the inner edges 42 of the sidewardly-spaced pair of wheelwell openings 41. The monolithic one-piece bed member 31 also includes front and rear secondary or side bed sections 48 and 49, respectively, which are respectively positioned forwardly and rearwardly of the wheelwell openings 41. The front secondary bed sections 38 are integrally joined to and project transversely from the main bed section 47 and extend longitudinally between the front edge 36 of the bed member and the front edge 43 of the respective wheelwell opening 41. The rear secondary bed sections 49 are also integrally and monolithically joined to and project transversely from the main bed section 47 and extend longitudinally of the bed member from the rear edge 44 of the respective wheelwell opening 41 to generally the rear edge of the bed member. These secondary bed sections 48 and 49 define thereon the longitudinally-extending side edges 38 of the bed member 31.

The bed member 31, due to the deforming thereof by longitudinal roll forming, has a plurality of longitudinally-elongate stiffening ribs 51 projecting upwardly from the plane of the thin sheet 35. A plurality of substantially identical such ribs 51 are generally uniformly sidewardly spaced apart in the transverse or widthwise direction of the main or central pan section 47, with the ribs 51 extending longitudinally of the pan 31 in generally parallel relationship. The ribs 51 have a generally inverted channel-like or U-shaped cross section, whereby each adjacent pair of ribs 51 define an elongate valley 50 therebetween, the base or bottom of the valley being defined by the original planar thin sheet 35. The ribs 51 project longitudinally throughout the entire length of the pan member 31 so as to terminate at the respective front and rear edges 36 and 37 thereof. These ribs provide the central floor pan section 47 with a substantially uniform transverse corrugated cross section throughout the entire longitudinal extent thereof.

As illustrated by FIG. 7, each rib 51 has a generally flat longitudinally-extending top wall 52 which extends transversely between and is joined to a pair of downwardly-projecting side walls 53, the latter pair of side walls preferably diverging with respect to one another as they project downwardly in sloped or angled relation relative to the respective top wall 52. These side walls 53 define sides of the respective valleys 50 which extend longitudinally of the pan member between adjacent ribs 51, and the bottom of the valley is defined by a base wall 54 which extends longitudinally between the front and rear free edges of the pan member and which also extends transversely between and integrally and monolithically joins to the lower edges of side walls 53 associated with two adjacent ribs 51.

While FIG. 7 generally illustrates the corrugated roll-formed cross sectional configuration of the floor pan 31, reference is made to FIG. 7A which more accurately illustrates the preferred corrugated cross section of the floor pan 31 which can be desirably achieved when the pan is roll formed in accordance with the present invention. By roll forming of the floor pan 31, it has been discovered that the side walls 53 which connect the top walls 52 and the base walls 54 need not be flat such as is conventionally required when the ribs are formed in a press, but rather the roll forming enables the side walls 53 to have a generally smoothly-curved S-shaped vertical configuration so as to provide a much more desirable transition between the top and bottom walls 52 and 54. The side wall 53 specifically includes an upper portion 85 which is of a generally circular arcuate convex configuration and a lower portion 86 which is also of a generally circular arcuate convex configuration, with these portions 85 and 86 being reversely oriented relative to their centers of radii, and effectively defining a smooth transition between the upper and lower walls. The upper arcuate part 85 specifically is formed so as to tangentially join to the upper wall at one end, and at its other end substantially tangentially joins to the upper end of the lower arcuate wall part 86. This lower arcuate wall part at its lower end then in turn tangentially joins to the lower wall 54. In this fashion, the side wall 53 in effect does not include any planar or straight portion in the vertical extent thereof, and the creation of the wall parts 85 and 86 by the rolling forming technique wholly eliminate sharp corners or bends and maintains uniform thickness of material throughout the cross section of the bed member. The radii defining the arcuate wall parts 81 and 82 are preferably substantially equal, and this radius will preferably have a magnitude which is about one-half the height of the rib 51, which magnitude is also many times (for example, at least an order of magnitude) greater than the thickness of the sheet material thickness.

In a preferred construction of the invention, the top walls 52 of ribs 51 preferably have a transverse width W1 which is at least equal to and more preferably greater than the transverse width W2 of the valley base walls 54. This thus permits the overall planar support area defined by the summation of the top walls 52 to be of significant magnitude to thus facilitate utilization of the vehicle bed since the upper surfaces of these top walls 52 thus effectively define the load-engaging plane of the bed member.

The side or secondary pan portions 48, 49 are also roll formed so as to have upwardly-projecting stiffening ribs associated therewith and projecting longitudinally of the pan member in generally parallel relationship with the stiffening ribs 51 associated with the central pan section 47. In the illustrated embodiment the side or secondary sections 48, 49 are provided with two sidewardly-spaced stiffening ribs, namely an intermediate stiffening rib 55 and an edge stiffening rib 56. These ribs 55 and 56 are roll formed into the pan member 31 simultaneously with the forming of the ribs 51, and the ribs 55 and 56 extend longitudinally and continuously between the front and rear edges of the pan member 31 prior to forming of the wheelwell openings 41 therein, substantially as illustrated by FIGS. 6 and 7. These ribs 55 and 56, however, after forming of the wheelwell opening 41 in the pan member, terminate at the front and rear edges of the wheelwell opening substantially as illustrated by FIGS. 8 and 9.

The intermediate rib 55 may be similar in shape and size as the ribs 51 and is disposed adjacent and sidewardly-spaced from the edge rib 56 through an intermediate base wall 57 connected therebetween, which base wall 57 is coplanar with and generally similarly corresponds to the base walls 54 described above. The edge rib 56, in the illustrated embodiment, has a side wall 53 associated with only one side thereof, and the top wall 52 of the edge rib 56 defines the longitudinally-extending side edge 38 of the finished pan member 31. This top wall 56, however, prior to forming of the wheelwell openings, has a flange 58 which is a monolithic and integral coplanar extension of the top wall 52, which flange 58 is subsequently deformed generally perpendicularly downwardly as indicated by dotted lines in FIG. 7 so as to define a securing flange 58 for attachment to the vehicle side wall 13.

The intermediate rib 55 is transversely joined to the transversely adjacent rib 51 of the central pan section 47 by a base wall 59 which extends longitudinally between the front and rear edges of the pan member and is generally coplanar with the other base walls 54 and 57. This base wall 59, however, preferably has a transverse width W3 which is significantly greater than the transverse width W2 of the base walls 54. In fact, the width W3 will preferably typically be at least about 1.5 times the width W2 and in fact may be as much as about 2.0 times the width W2.

As illustrated by FIGS. 5-6 and 8-9, the longitudinally-extending base wall 59 has the longitudinally-extending inner edge 42 of the wheelwell opening 41 formed therein, and the increased transverse width W3 of this base wall 59 facilitates the forming of the inner edge 42 therein, together with securing flanges which are subsequently deformed downwardly from the base wall 59 for securement to the wheelwell housing 41.

More specifically, and as illustrated by FIG. 8, the one-piece longitudinally-ribbed roll-formed pan member as illustrated in FIG. 6 is thereafter subjected to a notching operation which is for the purpose of forming the wheelwell openings 41 therein. This notching or punching operation initially results in formation of a modified wheelwell opening 41′, the edges of which are interrupted by cantilevered flanges or tabs which project generally horizontally coplanar from the pan member into the wheelwell opening. These flanges and tabs are then subsequently deformed downwardly in generally perpendicular relationship to the plane of the respective top and base walls of the pan member so as to provide the finished wheelwell opening 41 substantially as illustrated by FIGS. 5 and 9.

Referring again to FIG. 8, the forming of the modified opening 41′ in the side portion of the pan member results in the forming of a cantilevered flange 61 which is coplanar with the top wall 52 of the edge rib 56. The tab 61 projects longitudinally of the respective rib away from the respective front and rear wheelwell opening edges 43 and 44 so as to project into the region which will ultimately define the wheelwell opening 41. Similar and substantially identical flanges 61 are also coplanar with and integrally joined to the top wall of the intermediate ribs 55 and project longitudinally thereof beyond the wheelwell opening edges 43 and 44 into the region of the wheelwell opening 41. The intermediate base wall 57 also has a flange 62 integrally attached thereto and disposed in coplanar relationship therewith, with the flange 62 also being longitudinally cantilevered outwardly beyond the respective wheelwell edges 43 and 44 so as to project into the wheelwell opening 41. The flanges 62, however, are of shorter cantilevered extent or length than are the flanges 61, as illustrated in FIG. 8. In fact, the flanges 62 typically have a length which is less than the length of the flanges 61 by an amount which approximately corresponds to the height of the stiffening ribs so that when the flanges 61 and 62 are deformed downwardly as illustrated in FIG. 5, the lower free edges of the flanges 61 and 62 will be approximately at the same elevation.

The base wall 59 is also provided with a flange 63 which, after forming of the intermediate opening 41′ as illustrated in FIG. 8, is substantially coplanar with the base wall 59 and in fact originally comprises a part of the base wall 59. This flange 63 extends longitudinally a significant extent along the inner edge of the intermediate opening 41′, with this flange 63 being transversely (i.e. sidewardly) cantilevered only a relatively small distance. The sideward cantilevered distance approximately corresponds to the cantilevered length of the flanges 62, whereby downward displacement of the flange 63 into the position illustrated by FIG. 5 thus results in the forming of the longitudinally-extending inner edge 42 of the wheelwell opening 41.

The base wall 59, in the illustrated embodiment, adjacent each of the rounded wheelwell opening corners 45, is also provided with a further coplanar and cantilevered flange 64 which is disposed intermediate and spaced from the adjacent cantilevered flanges 61 and 63. The flange 64, due to its being coplanar with the base wall 59, also has a shorter length which generally corresponds to the cantilevered length of the flanges 62 and 63. These flanges 64 are also deformed downwardly into the position illustrated by FIG. 5 so as to define the wheelwell opening 41 as illustrated in FIG. 9, whereby the flanges 61, 62, 63 and 64 are thus all disposed for substantially abutting contact with and securement to the wheelwell housing 14, such as by welding.

The forming of the one-piece monolithic floor pan member 31, as illustrated in FIG. 4, will now be briefly summarized. The floor pan member 31 is preferably formed from thin steel sheet which during the roll forming process is a substantially continuous sheet supplied from a large coil. The width of the steel sheet is selected based on the desired transverse finished dimension of the pan member 31 so as to permit creation of the transversely corrugated floor pan including formation of the side edge flanges 58. The initial width of the flat steel sheet, as provided in the coil, thus substantially corresponds to the width of the finished floor pan member 31 if flattened out into a planar condition.

The flattened steel sheet is supplied from the coil into a roll-forming mill which, in a conventional and known manner, progressively reforms the flat steel sheet as it passes through the mill so that, upon leaving the mill, the steel sheet is longitudinally corrugated so as to have a cross section substantially as illustrated by FIG. 7. The continuous corrugated sheet is then fed to a cut-off press which cuts the continuous corrugated sheet at desired spaced distances corresponding to the desired lengths of the finished floor pan member 31. The separated floor pan member 31 has side portions which are free of wheelwell openings, and hence substantially correspond to FIG. 6. The separate roll-formed pan member is then moved into a forming station which effects notching of the modified wheelwell openings 41′ (FIG. 8) into opposite side portions of the pan member, which notching operation effectively removes a side central portion of the corrugated pan member to thereby result in formation of the opening 41′. Following the notching operation the pan member, having the modified wheelwell openings 41′ formed in opposite sides thereof, is then subjected to a pressing operation which effects cold working and hence downward deformation of the flanges and tabs 58, 61, 62, 63 and 64 to thereby provide a monolithic one-piece roll-formed corrugated floor pan 31 substantially as illustrated in FIG. 4. This floor pan 31 is thus generally in condition for securement to the cross rails 32, 33 and 34 in a conventional manner, typically by means of spot welds which are provided at the locations where the cross rails contact the base walls 54, 57 and 59.

The rear cross rail or sill 32 is preferably provided with a plurality of sidewardly-spaced protrusions 66 projecting upwardly therefrom, which protrusions are sized and positioned so as to project upwardly into the rearward ends of the ribs 51, 55 and 56, preferably directly adjacent the rear free edge of the pan member, so as to close off the rearward ends of the ribs and provide for supportive reinforcement of the ribs directly adjacent the rear edge of the bed. The protrusions 66 and their cooperation with the rear ends of the ribs can be generally in accordance with the disclosures contained in Assignee's prior U.S. Pat. Nos. 5,188,418, 5,544,932 and 5,575,525 as described above.

Alternately, and preferably, the rearward free edge of the pan member 31 is provided with a downwardly deformed flange 67 (FIGS. 10 and 15A) associated therewith and extending along the rear edge thereof. This rear flange 67 extends longitudinally along the entire length of the rear edge of the pan member and has an undulating configuration which corresponds to the corrugated cross section of the pan member. This flange 67 is positioned so as to project downwardly in overlapping relationship directly adjacent rear surfaces on the protrusions 66 and on the rear sill 32. This rear flange 67 preferably includes a rounded or arcuate portion which joins to the rear edge of the pan member and which is then smoothly curved downwardly for joining to a generally vertically projecting flange part 67A which overlaps the rear of the rear sill 32, with this latter flange part 67A terminating in a free edge. This rear flange 67 is disclosed and described in Assignee's copending U.S. application Ser. No. 08/661,062.

The bed member 31 of the invention, in a preferred embodiment, is also provided with a downwardly deformed front flange 87 (FIG. 15B) extending longitudinally therealong. This front flange 87 is constructed similar to the rear flange 67 in that it is integrally formed with and deformed downwardly from the plane of the bed member so as to provide additional reinforcement for the bed member due to the extension of this flange 87 across the front edge thereof. This front flange 87 is of a forwardly and downwardly rounded configuration so as to define a generally rounded front corner, with this rounded corner terminating in a generally lower but vertically planar flange part 88 which in turn defines a free edge 89. This generally vertically planar flange part 88 is adapted to generally abut against the front side wall 15 (FIG. 3) of the truck bed and can be fixed thereto, as by spot welding. Further, the shape of this front flange 87 and its cooperation with the adjacent vertical front wall 15 of the truck bed result in creation of a generally upwardly-oriented V-shape groove which extends longitudinally along the entire front edge of the pan member. This latter groove is used as a caulk-receiving groove to permit sealing of the pan member to the front wall.

The one-piece monolithic bed member 31 of the present invention, as illustrated by FIGS. 4 and 5, also preferably has a small notchlike opening 68 formed inwardly from one of the longitudinally-extending side edges thereof in longitudinally spaced relation from the respective wheelwell opening 41. This opening 68, which extends vertically through the side flange 58 and at least part of the edge rib 56, is sized so as to accommodate therein the externally-accessible fuel filling pipe which connects to the fuel tank of the vehicle. This notch 68 is preferably notched from the roll-formed pan member simultaneous with the formation of the adjacent notched wheelwell opening 41′.

To effect notching of the intermediate wheelwell opening 41′ as illustrated in FIG. 8, there is provided a notching arrangement 71 (FIGS. 11 and 12) which is designed specifically to cooperate with the roll-formed corrugated configuration of the pan member. This notching arrangement 71 includes respective upper and lower notch members 72 and 73 which cooperate to effectively sandwiched the side portion of the pan therebetween as illustrated in FIG. 11, prior to actual formation of the opening 41′. The lower member 73 is preferably stationarily supported on a suitable support frame (not shown), and is provided with an opening 74 vertically therein, the configuration of the opening 74 corresponding generally to the configuration of the wheelwell opening 41′. The upper surface 75 of the lower member 73 has a corrugated configuration which generally corresponds to the transverse corrugated or ribbed shape defined by the bottom surface of the pan member adjacent one longitudinally-extending side edge thereof so that the lower member 73, at least adjacent the front and rear edges of the wheelwell opening and also along the longitudinally-extending inner edge thereof, supportively engages the underside of the ribs 55 and 56 as well as the base walls 57 and 59. This lower member 73 also has appropriate cantilevered support tongues 81, 82, 83, 84, which are positioned and shaped corresponding to the flanges 61, 62, 63 and 64, respectively.

The upper notch member 72 is sized and positioned so as to be disposed directly over the opening 74 in the lower member 73, and the upper notch member 72 is connected to a vertical driving device 77 which effects downward movement of the upper member 72 into the opening 74 so as to effect creation of the opening 41′. The upper member 72 has a outer generally U-shaped edge which generally corresponds to the shape of the opening 41′ to thus effect shearing or punching of the roll-formed edge portion of the pan member to effect formation of the opening 41′. The bottom surface 78 of the upper member 72 is also provided with a corrugated or ribbed configuration which generally corresponds to the corrugated upper surface of the engaged area of the pan member 31, substantially as illustrated by FIG. 11, so that the downward movement of the upper member 72 effects substantially simultaneous punching of the pan member around the entirety of the opening 41′. The top and base walls, as well as the interconnecting side walls, are thus all substantially simultaneously punched so as to create the opening 41′. This simultaneous notching of the entire nonuniform edge of the opening 41′, together with the accompanying supportive engagement provided by the lower member 73 around the entirety of the edge of the opening 41′, together with the pressing engagement provided by the upper member 72 around the entirety of the inner perimeter of the opening 41′, permits the opening 41′ to be accurately formed without creating any significant dimensional change or deformation of the pan member in the vicinity of the opening 41′, particularly where the ribs 55 and 56 terminate at the front and rear edges of the wheelwell opening.

Further, by provision of the increased width W3 of the base wall 59 and the positioning of the longitudinally-elongate inner edge 42 of the wheelwell opening therealong, this wider base wall 59 contains sufficient material to also permit formation of the flanges 63 and 64 therefrom, and in fact all of the flanges 6-64 are formed from horizontally planar walls of the pan member, even though sloped side walls 53 of the ribs are sidewardly interposed between some of the flanges, such as the rib side wall which is disposed between the flange 62 and the flanges 61 as disposed on opposite sides thereof.

Referring now to FIGS. 13A-13C, there is diagrammatically illustrated the process for forming the edge flanges which are associated with the longitudinal side edges and the wheelwell openings, such as the flanges 58, 61, 62, 63 and 64. FIGS. 13A-13C illustrate the formation of the flange 63 which extends along the longitudinally-extending inner edge of the wheelwell opening, but it will be appreciate that the arrangement and process illustrated by these figures are also applicable to the other flanges.

Referring specifically to FIG. 13A, the roll-formed bed member 31 is positioned in a flange forming apparatus 90 which includes upper and lower supports 91 and 92 which clampingly engage therebetween that portion of the pan member 31 adjacent the flange, such as the flange 63, with the flange being positioned so as to project in cantilevered fashion outwardly beyond the supports 91 and 92. A pair of movable forming or wiping members 93 and 94 are disposed adjacent the supports for supportive engagement with the respective upper and lower surfaces of the projecting flange 63. The flange 63 is closely but transversely slidably confined between the opposed faces of the moveable wiping members 93 and 94, and the upper wiping member 93 has an inner face or surface 96 which is spaced from an opposed side face of the adjacent upper support 91 so as to define a small vertically extending gap 96 therebetween, which gap has a dimension which closely approximates the thickness of the flange 63. To effect downward deformation of the flange into a position wherein it projects downwardly in perpendicular relationship to the plane of the pan member, the wiping or forming members 93, 94 are synchronously moved downwardly by a driving device (not shown) which maintains the opposed faces thereof closely spaced so as to confine the flange 63 therebetween. As these forming members 93, 94 are moved downwardly, however, this downward movement and the presence of the gap 96 are such that the flange 63 starting at its juncture with the main pan member is progressively deformed downwardly along the flange toward the free end thereof, this in actuality being a cold working of the metal similar to a roll-forming technique. The wiping members 93 and 94 are thus moved downwardly through a sufficient stroke until the flange 63 is deformed or drawn downwardly to its free end or tip and hence effectively is totally pulled out of the gap between the wiping members 93, 94 and assumes an entirely perpendicular relationship as illustrated by FIG. 13C.

With the formation of the flange by actual progressively deforming or cold working the flange from the junction point with the pan, to the tip end of the flange, this thus enables the thickness of the flange including at the corner connection to the pan member to be maintained uniform, and also effectively sufficiently reworks the metal of the flange such that when the pan member 31 is removed from the forming apparatus 90, the flange 63 will accurately retain its downwardly projecting perpendicular relationship and will not experience any significant spring back or deformation due to residual stresses created in the flange.

By forming all of the flanges (i.e. flanges 58, 61, 62, 63, 64, 67, 87) by means of a deforming cold working process similar to that illustrated by FIGS. 13A-13C, the flanges hence all possess properties which are generally equivalent to the roll-formed properties of the pan, and result in the flanges having a significantly higher degree of dimensional accuracy so as to greatly facilitate the positioning of the pan on the vehicle and the welding of the pan to the vehicle side walls and wheelwell housings due to the accuracy of manufacture achieved by this invention.

The overall flange forming apparatus 90 is diagrammatically shown in greater detail in FIG. 14 wherein there is illustrated the lower support 92 being stationarily provided on a base or support frame 97, with the wiping member 94 being movably supported on the base 97 and resiliently urged upwardly by a suitable spring 98. The upper wiping member 93 is coupled to the lower end of a driving device 99, such as a variable speed fluid pressure cylinder, the housing of which is mounted on a top slide 101, the latter being horizontally slidably supported on the base 97. The top slide 101 can be movably displaced inwardly toward the bed member 31 so as to be disposed in a position for cooperation therewith substantially as illustrated by FIG. 14, and when not in use the slide 101 can be retracted outwardly (rightwardly in FIG. 14) so as to not be disposed over the bed member so that the latter can be suitably vertically raised by an appropriate lift-and-carry conveying system. A suitable driving device 102 such as a pressure cylinder cooperates between the base 97 and slide 101 to control the horizontal movement of the latter. Springs 103 are also preferably provided between the top support 91 and the top wiping member 93 to maintain the support 91 clampingly engaged with the upper surface of the bed member 31, while at the same time enabling the top slide 93 to move downwardly to effect drawing or forming of the flange substantially in the manner illustrated by FIGS. 13A-13C.

While FIGS. 13A-13C illustrate forming of a flange with a rather sharp corner, it will be appreciated that this same process and apparatus can be used for forming a flange having a more rounded corner, such as the rear flange 67 or the front flange 87, which more rounded corner is accommodated by providing a more rounded forming corner on the lower support 92.

The process and apparatus for permitting overall forming of the pan member 31, and the attachment thereof to the cross rails 32-34 to effectively create a bed assembly, will now be described with reference to the diagrammatic plan view of FIG. 17 and process chart of FIG. 18.

The main floor pan 31 is formed from thin sheet steel which during the forming process is a substantially continuous sheet supplied from a large coil. The width of the sheet steel is selected based on the desired finished dimension of the formed floor pan 31 so as to permit creation of the corrugated floor pan including formation of the side edge flanges 58 thereon, whereby trimming of the sheet or finished pan is unnecessary. The initial width of the flat steel sheet, as provided in the coil, thus substantially corresponds to the width of the finished floor pan if flattened out into a planar condition.

The steel sheet is normally supplied in the form of a large coil 121 as provided on a coil feed rack 122 which can be positioned adjacent a cradle 123 onto which the coil 121 can be transferred for support during the manufacturing operation. The cradle 123 has conventional structure associated therewith to effect strengthening of the sheet material as it is discharged therefrom in the form of a substantially continuous sheet 124. The sheet material is feed through a combined end shear-welder 125 which trims the leading and trailing ends of each coil and welds the trimmed trailing end of one coil to the leading trimmed end of the next coil to permit a substantially continuous sheet 124 to be fed into and through the subsequent manufacturing stations.

After passing through the shear/welder 125, the continuous sheet steel 124 progressively moves through a roll mill 126 which progressively reforms the steel sheet so that, while the steel sheet is substantially flat when entering the leading end of the roll mill 126, the steel sheet is suitably formed so as to have the finished cross section of the floor pan 31 when leaving the discharge end of the roll mill 126. This progressive reforming of the steel sheet as it passes through the mill 126 is diagrammatically illustrated by the progressive decreasing width of the steel sheet as it moves longitudinally through the mill 126.

Upon leaving the roll mill 126, the continuous steel sheet 124 has now been formed so as to have the corrugated cross section of the pan 31 substantially as illustrated by FIG. 7, which corrugated cross section includes the flange parts 58 extending longitudinally along opposite sides of the floor pan, which parts 58 are substantially horizontally coplanar with either the top or bottom walls of the corrugated pan. These parts 58 are subsequently deformed to permit formation of the downwardly-projecting side flanges 58 as described hereinafter.

The continuous corrugated sheet as discharged from the roll mill 126 is fed into and through a conventional cut-off press 127 which cuts the corrugated steel sheet at desired spaced distances substantially corresponding to the desired length of the finished floor pan 31. The now separated floor pan 31 is then transferred to conveyors 128 and 129, which conveyors effect a speed-up in the velocity of the separate floor pan 31 downstream of the cut-off press 127 to effectively separate it from the leading edge of the continuous roll-formed sheet 124.

The conveyor 128-129 moves the separated floor pan 31 to a transfer device 131 which moves the pan member 31 to a transfer station 132, the latter cooperating with one end of a transfer conveyor 133, such as a conventional overhead lift-and-carry conveyor. This conveyor 133 can engage and lift the bed member 31 located at the transfer station 131 and move the member sidewardly, that is in a direction generally perpendicular to the longitudinally extending direction of the bed member. This conveyor 133 shifts the bed member 31 to a press station (i.e. a notching and piercing) 134 where secondary stamping operations are carried out on the pan member, which secondary stamping operations primarily include piercing and notching of the pan member. After completion of the desired stamping operations at station 134, the pan member is then transferred as by the transfer device 133 to the next station 135, this being a flanging station for permitting creation of the downwardly turned flanges associated with the side, front and rear edges of the bed member. Upon completion of this flange forming operation, the roll-formed bed member 31 is now substantially completed, and is moved by the transfer mechanism 133 to a direction changing station 136. At this station 136 the pan member is positioned on a conveyor 137 which advances the pan member to an inspection station 138 whereat the dimensions of the finished pan member are inspected, such as by use of laser inspection devices. The conveyor thereafter advances the pan member to a dwell station 139, from which the pan member is engaged and forwardly advanced by a further conveyor 141, such as a conventional overhead lift-and-carry conveyor. The latter conveyor advances the pan to a loading assembly station 142 for positional assembly of the bed member to the cross rails 33-34. For this purpose, the cross rails 33-34 can be stored in racks such as diagrammatically illustrated at 143 with the rails being removed from the rack 143 and positioned on a positioning fixture 144 which is disposed sidewardly of the loading station 142. An appropriate transfer mechanism then automatically transfers the rails from the station 144 to the loading station 142, with the bed member being moved into and properly positioned at the loading station 142 so as to define a proper positional relationship between the rails and bed member. The positionally assembled bed and rail assembly at loading station 142 is then transferred by a conveyor 145 to a first welding station 146 which effects spot welding of the rails to the bed member. The first welding station 146 normally effects spot welding between the rails and the bed member solely along the longitudinally extending center portion of the bed member. The assembly then is transferred to the next welding station 147 which effects further spot welds between the rails and bed member outwardly from the spot welds created at the station 146. The assembly is then transferred to still a further welding station 148 which creates further spot welds between the rails and bed member, these latter spot welds being disposed adjacent the opposite longitudinally extending outer portions of the bed member. The bed assembly is then transferred from weld station 148 by conveyor 145 to an inspection station 149 which carries out a final dimensional inspection of the assembly, again typically by laser sensing devices. The assembly is then discharged by the conveyor to a discharge station 150, from which it can be transferred to suitable conveying devices for supply to a vehicle assembly line, or in the alternative transferred into suitable storage racks or the like.

The forming operations associated with the bed member at the press station 134 will now be described in greater detail, specifically with reference to FIG. 19.

When the roll formed bed member 31 is transferred into the press station 134, it is initially clampingly engaged by top and bottom clamps as indicated at 221, which clamps extend transversely across the upper and lower surfaces of the bed member adjacent at least the opposite ends thereof, with the clamps having a corrugated configuration compatible with that of the bed member to permit secure clamping engagement with the bed member. After the bed member has been suitably clamped at the press station 134, then piercing operations on the bed member are initiated at 222, which piercing operations involve the formation of several holes or openings vertically through the bed member. For example, a pair of cooperating alignment holes 161 and 162 (FIG. 16) are formed through the bed member adjacent one side thereof, with a further such pair of holes being formed adjacent the other side of the bed member in the preferred embodiment. The one hole 161 as disposed adjacent the rear corner is a round alignment hole, whereas the other hole 162 as disposed adjacent the front corner is an elongate slot which is generally aligned with the hole 161. Additional holes can also be formed through the bed member, such as drain holes if desired, the latter being indicated at 163, or in some cases there is a desire to also provide bolt holes (not shown). All of these holes can be substantially simultaneously pierced through the bed member by conventional piercing tools.

Following the piercing, the front and rear end edge are preferably trimmed (i.e., sheared) at 223 to ensure the accuracy thereof.

The bed member is also thereafter subjected to notching operations (step 224) along the peripheral edges thereof while located at the press station 134. For example, and referring to FIG. 16, the wheelwell openings 41 are formed in the opposite longitudinally extending side edges of the bed member, these being created substantially as enlarged notches generally in accordance with an arrangement similar to that illustrated by FIGS. 11-12 as described above. Each rear corner of the bed also has a notch 165 formed therein so as to accommodate the reinforcing post structure associated with the rear end of the truck bed side wall. When the truck bed is being provided with a front flange such as the flange 87 of FIG. 15B, then each front corner of the truck bed is also provided with a small notch 166 therein so as to prevent interference between the front flange 87 and side flanges 58 during the subsequent forming thereof. The fuel filler tube opening 68 is also notched in one of the side walls of the bed. All of these notches are formed substantially simultaneously using shear-type notching tools configured so as to provide the desired notch profile.

It is preferred to first initiate the aforementioned piercing operation, with the piercing operations being at least partially completed before initiating the notching operation so as to minimize the amount of material distortion force which is simultaneously applied to the bed member. Further, by initiating and at least partially completing the piercing operations prior to initiating the notching operations, the piercing tools can be maintained in secure gripping engagement with the bed member and thus assist in maintaining the rigidity of the bed member as the notching operations are being performed.

After all of the piercing and notching operations have been performed at the press station 134, the roll formed bed member will have an appearance similar to that illustrated in FIG. 16, which bed member has not yet been subjected to any drawing or wiping operations for forming the downwardly projecting edge flanges.

The bed member in the condition illustrated in FIG. 16 is transferred from the press station 134 to the flange forming station 135 so as to effect downwardly drawing or wiping of the various edge flanges. As the bed member is moved into the flange forming station 135, it is initially accurately positioned due to a pair of upwardly projecting alignment pins at the station 135 being inserted through one of the alignment holes 161 and its corresponding alignment slot 162 (step 226 of FIG. 20). This thus provides for precise positioning of the bed member at the flange forming station 135. The bed member is then suitably clamped (step 227) by top and bottom clamp members to facilitate the stationary securement of the bed member.

Thereafter the flange forming devices 90A (FIG. 18) as disposed adjacent opposite side edges of the bed member are activated (step 228) so as to effect downward drawing or wiping of not only the side flanges 58, but also of the flanges 61-64 associated with the wheelwell openings. These flanges are wiped or drawn downwardly in a cold working fashion by the arrangement 90 which is illustrated generally by FIGS. 13 and 14 as described above.

After the side edge flanges have been drawn downwardly, then the side flange forming apparatus 90A are maintained in the extended position so that the opposite side flanges are effectively held in the respective drawing apparatus, substantially as illustrated in FIG. 13C, and then the front and rear flange forming apparatus 90B are activated (step 229) to effect forming of the rear flange 67 and front flange 90. Since the rear flange extends along the corrugated configuration of the roll formed bed member and requires imposition of greater forming force in order to effect downward drawing of the flange, the maintaining of the bed member sidewardly clamped between the side flange formers 90A provides additional overall securement and rigidity to the bed member during the rear flange forming operation. After the front and rear flanges have been suitably formed, then all of the flange forming apparatus 90A and 90B are retracted upwardly, and then retracted horizontally outwardly away from the bed member, following which the bed member is then lifted and transferred to the next station 136.

If the bed is not being provided with a front flange, then the front flange forming apparatus 90B is either omitted or not activated. Further, while the invention as described above relates to forming of the front flange by a wiping or drawing process, and while such is preferred, nevertheless the structure of the front flange is less critical and such flange can be formed by a conventional bending operation if desired.

During the subsequent transfer of the bed to and between the weld stations, the alignment holes 161 and slots 162 are utilized to ensure proper positioning of the bed member both during the transfer between stations and for positioning at the work station. For example, each of the welding station is provided with a pair of upwardly projecting alignment pins which engage the hole 161 and slot 162 associated with one side of the bed member to ensure proper positioning of the bed member at the welding station. On the other hand, during transfer of the bed member to or between the weld stations, the alignment hole and slot 161-162 provided adjacent the other side of the bed member cooperate with alignment pins associated with a walking beam shuttle which is part of the lift-and-carry transfer conveyor 45 so as to maintain proper positioning of the bed member during transfer thereof between adjacent workstations.

The welding of the cross rails or sills to the bed member, as depicted by the stations 146-148, is generally conventional.

Modified rear edge constructions for the roll-formed bed member will now be described with reference to FIGS. 21-23, and the process for forming these modified rear edge constructions will be described with reference to FIGS. 24-28.

Referring specifically to FIGS. 21-22, there is illustrated a modified rear edge construction for the roll-formed bed member 31, which bed member is illustrated with its rear edge portion supported on a conventional rear rail or sill 32 which extends transversely under the bed member. In this rear edge construction, the bed member 31 is provided with a flat and substantially planar flange 67A extending transversely across the bed, which flange 67A terminates at the rear free edge 37 of the bed member. The flange 67A is defined by deforming and hence flattening rear portions of the ribs 52 over a selected longitudinal length which projects forwardly from the rear edge 37.

The bed member 31 of the FIGS. 21-22 in addition has the ribs 51 thereof, just forwardly of the flange 67A, downwardly deformed so as to define tapered rib portions 51A which extend longitudinally of the bed member over a small distance, and define a transitional zone between the rear flange 67A and the longitudinally-extending full-height ribs 51. The tapered rib portions 51A each have a top wall 52A which at one end is continuous with and joins to the top wall 52 of the full-height ribs 51, with this top wall 52A then angling or sloping downwardly as it projects rearwardly until intersecting the plane of the bed member base walls 54, which intersection substantially defines the transition between the tapered rib portions 51A and the rear flange 67A. The tapered rib portions 51A thus effectively define a slope or ramp which projects upwardly from the elevation of the base walls 54 to the elevation of the rib top walls 52, with this ramp projecting in a forward direction as it slopes upwardly to thus eliminate or minimize any abrupt or sharp corner at the rear of the bed member.

The tapered rib portions 51A are shaped by physically deforming a selected length of the full-height ribs 51 downwardly into the tapered or sloped configuration, as explained hereinafter. Since this downward deforming (i.e. compressing) of the ribs into the tapered configuration results in at least partial collapsing of the side walls of the ribs, it is preferred that the tapered rib portions 51A, as defined by the top walls 51A thereof, slope or angle relative to the horizontal at an angle of at least about 30°, which slope or angle may be increased to about 40°, so as to minimize the amount of material which is being physically displaced during the compression of the ribs into the tapered shape.

With the modified end construction of the bed member as illustrated by FIG. 21, the rearward portions of the ribs 51 as well as the tapered rib portions 51A are disposed so as to seat on the upper surface 32B of the rear sill 31, and the rear flange 67A is deformed downwardly so as to effectively overlie the rear surface 32A of the rear sill 32. The bed member is then secured to the rear sill in a conventional manner, as by spot welding at selected locations, as generally described above.

If desired, the upper surface 32B of the rear sill can be provided with riblike projections thereon for interfitting into the ribs 51 and tapered rib portions 51A, similar to the projections associated with the rear sill illustrated in FIG. 10 above. However, in many applications the projections on the upper surface of the rear sill may be eliminated since the tapered configuration of the rear rib portions 51A and the additional strength provided by this configuration, coupled with the additional cold working and hence the additional strength provided by the tapered rib portions as a result of the deforming thereof, will result in the rear edge of the bed member having improved strength and rigidity.

FIG. 23 illustrates therein a further modification of the rear edge construction of the roll-formed bed member 31, and its cooperation with the rear sill 32. The rear edge construction illustrated in FIG. 23 is substantially identical to the rear edge construction illustrated in FIG. 21 in that it again includes a flat and substantially planar rear flange 67B which extends transversely across the bed member at the rear free edge 37 thereof, and this flat rear flange 67B joins to the full-height longitudinally-extending ribs 51 through tapered rib portions 51A which slope upwardly as they project forwardly and extend through a small longitudinal distance. The primary difference between the rear edge constructions of FIGS. 23 and 21 is the fact that the rear flange 67B of FIG. 23 is not bent downwardly, but rather remains substantially coplanar with the bottom walls 54 of the bed member, whereby when the bed member is positioned on the rear sill the rear flange 67B is disposed so as to directly overlie the upper wall 32B of the rear sill 32.

To form the bed rear edge construction illustrated in FIG. 23, the bed member 31, after it has been rolled-form and cut to length, is then subjected to a deforming operation along the rear edge thereof by means of a forming apparatus 301 as illustrated in FIGS. 24-25. This forming apparatus 301 includes upper and lower forming members or dies 302 and 303 respectively, which are disposed in opposed relation for permitting the rear edge portion of the bed member 31 to be positioned and engaged therebetween. These support members or dies 302 and 303 are transversely elongated so as to extend across and be engageable with the rear end portion of the bed member 31 across substantially the full width thereof. The lower die 303 has a generally flat upper surface 304 adapted for supportive engagement with the bottom walls 54 of the bed member. A plurality of riblike supports 305 protrude upwardly from the upper surface 304, which protrusions 305 are disposed in sidewardly spaced relationship so as to correspond with the individual ribs 51 as defined in the bed member. The protrusions 305 are shaped and sized in cross section so as to individually project into and provide support for the individual rib members 51 when the bed member is engaged with the bottom die 303. These protrusions 305 have a tapered edge 306 which slopes downwardly for merger with the upper surface 304 at a point spaced from the rear edge of the die member, thereby leaving a portion 304A of the upper surface free of the protrusions.

The upper support or die member 302 is disposed in vertically opposed relationship to the bottom die 303 and defines thereon a bottom shaping or deforming surface which extends lengthwise of the upper die member in transverse relationship to the bed member, with this bottom surface including a front substantially flat and horizontal surface 308 which joins to a flat and planar intermediate surface 309 which slopes downwardly as it projects rearwardly, and this intermediate surface 309 in turn joins to a flat and substantially horizontally planar rear surface 310. The flat surfaces 308 and 310 are generally parallel and spaced apart by a distance which substantially corresponds to the height of the ribs 51, and the sloped intermediate surface 309 extends in generally parallel relationship with the sloped surface 306 on the projections 305 so as to permit forming of the tapered rib portion top wall 52A therebetween.

To deform the rear edge portion of the roll-formed bed member 31, the bed is positioned between the dies 302 and 303 so that the protrusions 305 project up into the interior of the ribs 51, whereby the base walls 54 of the bed member thus seat on the top surface 304. The bed member is preferably positioned so that the rear free edge 37 thereof is disposed in supportive engagement with the surface area 304A. The upper die member 302 is then moved relatively downwardly by a driving device 311 such as a plurality of fluid pressure cylinders, thereby causing the lower surface 310 of the upper die to initially contact the rib top walls 52 over a predetermined distance directly adjacent the free rear edge 37. The downward driving of the top die 302 causes downward compression and hence flattening of the rear portions of the ribs between the opposed surfaces 304A and 310 so as to result in formation of the flat and substantially planar rear flange 67B, the latter being substantially coextensive and coplanar with the bottom walls 54. During this flattening of the rear flange, the upper sloped die surface 309 also progressively moves into contact with the top wall 52 of the respective ribs over a selected length thereof and effectively causes a progressive downward deforming of the top rib wall, and of the associated rib side walls, causing the top wall to assume the downwardly sloped or tapered configuration 52A due to its being deformed between the opposed sloped surfaces 306 and 309. During this downward pressing of the top die 302, the top wall 307 of the protrusions 305 remain in supportive engagement with the underside of the rib top walls 52 until the opposed flat surface 308 moves into contact with the upper surfaces of the top rib walls 52, thereby effectively signalling a completion of the first deforming or re-striking of the rear portion of the rolled-formed bed member. When the die 301 is opened and the bed member removed, the rear edge portion of the bed member in side elevation thus has a configuration which generally resembles the configuration illustrated by FIGS. 23 and 26.

Thereafter the rear edge portion of the bed member 31 is positioned for engagement by a further forming device or die 311 (FIGS. 26-27), the latter including upper and lower die members 312 and 313 which are relatively movable toward one another for creating a working engagement with the rear edge portion of the bed member which is engaged therebetween. The lower die 313 is substantially identical to the lower die 303 described above in that it has a substantially flat and planar upper surface 314 provided with a plurality of sidewardly spaced protrusions 315 projecting upwardly therefrom, the latter being sized and shaped so as to project supportingly into the interior of the rearward and tapered end portions of the ribs 51. The upper die 312 has a substantially flat and planar bottom surface 316 which is substantially parallel with the top surface 314 of the lower die. The bottom surface 316, however, has a plurality of grooves 317 which are formed therein and opening upwardly therefrom, which grooves 317 are sidewardly spaced along the transverse length of the upper die so as to generally align with the individual ribs 52. The grooves 317 have a shape which generally corresponds to the shape of the protrusions 315 except for being somewhat larger in cross section so as to accommodate the additional thickness of the wall defining the rib 51. The upper die 312 is moved downwardly by a driving device, such as a plurality of fluid pressure cylinders 318 so as to pressingly captivate the end portion of the bed member 31 therebetween. During the downward moving of the upper die 312 toward the lower die 13, the latter having the rear edge portion of the bed member positioned thereon, the wall structure defining the groove 317 engages and effectively re-strikes the wall defining the end of the rib 51, particularly the tapered rib portion 51A, so as to effect reshaping of the side walls of the rib portions 51A as they extend vertically between the tapered top wall 52A and the base walls 54, thereby providing a shape consistent with the shape of the ribs 51 and eliminating or at least greatly minimizing any deformation lines and surface irregularities created during the first re-striking of the rib ends. In particular, since the collapsing of the rib ends into a tapered shape results in excess material, particularly along the side walls of the ribs, the second re-striking of the tapered rib ends by the die 311 provides for more effective deforming and reworking of the side walls of the tapered rib portions so as to provide both improved strength and uniformity and improved exterior visual appearance.

After the second re-strike die 311 is opened and the bed member 31 removed, the bed member thus has the configuration illustrated by FIG. 23 and can then be secured to a rear sill.

To permit forming of the rear edge portion of the bed member 31 so as to have the configuration illustrated in FIG. 21, the roll-formed and cut-to-length bed member 31 is again initially subjected to a first re-strike by means of the die member 301 (FIGS. 24-25) as described above. The bed member is then subjected to a second re-strike by means of the die arrangement 321 illustrated in FIG. 28. This die arrangement 321 includes an upper die member 322 which has grooves 327 opening upwardly from the bottom surface 326 thereof, and a bottom die member 323 which has protrusions 325 projecting upwardly from the upper surface 324 thereof. The configuration of the upper and lower dies 322 and 323 is substantially identical to the configuration of the dies 312 and 313 so as to permit a second re-striking of the tapered rib portions and thus permit proper reshaping of the side walls of the tapered rib portions. To control the downwardly forming of the rear flange 67A, however, the upper die 322 has a separate die part 331 which has a substantially planar lower surface 332 adapted for contacting the upper surface of the flange 67A when it is coplanar with the bottom walls 54. This moving die part 331 is opposed to a bottom moving draw pad 333 which has a planar top wall 334, which draw pad 333 is normally urged upwardly by springs 335 which permit downward displacement of the lower pad 333. With this die 321, the upper shoe 336 is moved downwardly to effect clamping of the rear edge portion of the bed member between the opposed die parts 322 and 323, with the protrusions 325 projecting into supportive engagement within the ribs 51 from below, and the grooves or recesses 327 engaging exteriorly over the rib end portions to effect re-working or re-striking of the tapered rib portions, particularly the side walls thereof, as explained above relative to FIGS. 26-27. When the die parts 322 and 323 have the bed end member securely clamped therebetween, then the upper shoe 336 is further moved downwardly by a driving device (not shown) such as fluid pressure cylinders whereby the flange 67A is held between the pads 331 and 333 which cause a progressive downward forming of the flange 67B until it is downwardly deformed in its entirety, this downward forming being substantially identical to the flange-forming arrangement illustrated by FIGS. 13A-13C above.

With the rear end portion of the bed member 31 subjected to re-striking after it has been roll-formed and cut to length, particularly when subjected to the two re-striking operations described above so as to result in formation of a tapered rib portion at the rear end, as illustrated by FIGS. 21 and 23, the rear end portion still maintains a uniform wall thickness throughout the ribs at least equivalent to the initial sheet material thickness used for forming the bed member, and in fact the partial flattening of the ribs throughout the tapered rib portions in actuality results in excess material which, during the re-striking operations, is redistributed so as to result in some increase in material thickness, particularly in the side walls of the tapered rib portions. This increased material thickness, coupled with the cold working of the material caused by the first and second re-striking operations, thus provides the edge portion of the bed member with increased strength and rigidity, and thus provides improved durability.

The additional re-striking of the rear edge portion of the bed member, and particularly the first re-striking step as depicted by FIGS. 24-25 and the second re-striking step as depicted by FIGS. 26-27 or FIG. 28, are preferably integrated into the overall bed-forming process illustrated by FIG. 18. For example, the first re-strike as illustrated by FIGS. 24-25 is preferably carried out at the pierce end notch station as indicated at 204 in FIG. 18, and thus can be substantially simultaneously or sequentially performed along with the other piercing and notching operations being carried out at this station. Following transfer of the bed member to the flange forming station 206 (FIG. 18), then the second re-strike of the bed member as carried out by dies as illustrated by FIGS. 26-27 or FIG. 28 is preferably carried out, either simultaneously or sequentially with the other flange forming operations being carried out at this station. These additional re-strike operations for reshaping the rear edge portion of the bed member can thus be carried out without requiring any separate work handling or work processing stations, and without significantly increasing the amount of time required to carry out the additional operations on the bed member when located in the notch and pierce station or the flange forming station.

It will further be appreciated that the rear edge construction of the bed member as depicted by FIGS. 21 and 23, and the forming processes therefor, can be utilized for creating a roll-formed bed member irrespective of whether the bed member is, or is not, provided with wheelwell openings formed in the opposite sides thereof.

The rear edge construction of the rolled-formed bed member illustrated in FIGS. 21 and 23 can also be provided at the front edge of the bed member if desired, although providing such edge construction and undertaking the additional steps required for doing so is normally considered unnecessary for the front edge of the bed for most vehicles.

While the invention as described above relative to the one-piece monolithic pan 31 contemplates that the roll-formed member will be formed from sheet steel, it will be appreciated that the invention also permits the floor pan member to be formed from laminated sheet material such as sheet steel having a plastic sheet layer laminated over the top thereof since such construction may eliminate the need for a separate bed liner.

It will also be appreciated that while the invention as described above references the upward formation of the stiffening ribs from the flat sheet material, it will be appreciate that the relative deformation of the sheet material and forming of the ribs is such that the original planar sheet material can in actuality define the flat top walls of the ribs, and that the actual deforming of the sheet material can be a downward deformation of the valleys between the ribs.

While the invention has been described for use on and is particularly adaptable for use on a pickup truck, it will be appreciated that the invention is also particularly adaptable for use on other vehicles which require a similar bed construction, such as vans and sport utility vehicles.

Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention. 

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A process for forming a bed assembly for a truck, comprising the steps of: providing a wide and continuous flat sheet of thin metal; roll forming said continuous flat metal sheet in the lengthwise extent thereof to define a plurality of generally parallel, sidewardly-spaced, downwardly-opening, channel-like stiffening ribs therein across substantially the entire width thereof and sidewardly spaced apart by upwardly-opening channel-like valleys having bottoms which define a base wall, with said stiffening ribs and valleys extending uniformly and longitudinally throughout the entire length of the formed metal sheet as said formed sheet is moved longitudinally through and discharged from a rolling mill; severing the continuous formed sheet into elongate bed members of predetermined longitudinal length having said stiffening ribs and valleys extending longitudinally throughout the length thereof so that the bed member has corrugated front and rear free edges thereon; reshaping longitudinally-extending rear portions of said ribs which extend forwardly a predetermined distance from said rear free edge so that said rear rib portions define tapered rib portions having top walls deformed downwardly so as to slope downwardly from rib top walls toward and merge into the base wall of the bed member as the tapered rib portions project longitudinally rearwardly toward said rear free edge so as to close off the ends of said ribs; the step of reshaping including forming a generally flat rear flange which is coplanar with the base wall of the bed member and which projects rearwardly from rearward ends of said tapered rib portions and terminates at said rear free edge; the step of reshaping also including confining and shaping sidewalls of the rib end portions to maintain the preformed valleys between the ribs during the reshaping of the rib end portions; and thereafter fixedly securing said bed member in supportive engagement over a plurality of spaced but generally parallel transverse rails associated with the bed of a truck.
 2. A process according to claim 1, wherein the steps of reshaping the rear portions of the ribs and forming the rear flange occur essentially simultaneously.
 3. A process according to claim 1, wherein the step of fixedly securing includes fixing the rear flange on a upper wall of a rearmost one of the transverse rails.
 4. A process according to claim 1, wherein the step of forming the rear flange includes subsequently forming the rear flange so that it extends downwardly from the metal sheet.
 5. A process according to claim 4, wherein the step of fixedly securing includes overlying the rear flange on a rear wall of a rearmost one of the transverse rails.
 6. A process according to claim 1, wherein the step of reshaping the rear portions of the ribs includes engaging a first reshaping member on the top walls of the tapered rib portions so that they angle downwardly, and thereafter engaging a second reshaping member on the tapered side walls of the tapered rib portions to effect final working and shaping of the tapered rib portions.
 7. A process according to claim 1, wherein the step of reshaping includes positioning the formed sheet between upper and lower reshaping members, inserting protrusions on the lower reshaping member from below into the interior of the ribs forwardly of the predetermined distance to support the ribs during the formation of the tapered rib portions, and contacting protrusions on the upper reshaping member onto the ribs from above throughout the predetermined distance so that as the upper reshaping member moves toward the lower reshaping member the end portions of the ribs are deformed so as to form said tapered rib portions.
 8. A process according to claim 1, wherein the step of reshaping includes displacing the top walls of the ribs at the rear portions thereof from generally parallel to the flat sheet to an angle of about 30 to 40 degrees to the flat sheet.
 9. A process for forming a monolithic one-piece vehicle bed member, comprising: providing a wide and longitudinally elongate flat sheet of steel having a thickness of at least about 0.8 mm; providing a roll mill capable of progressively reforming a flat sheet in the longitudinal direction thereof as the sheet passes through the roll mill; feeding the flat steel sheet in a lengthwise direction into and through the roll mill to progressively longitudinally reform the sheet into a three-dimensional workpiece member having a flat base wall and a plurality of substantially sidewardly displaced and parallel channel-like ribs which project upwardly from the base wall and open downwardly thereof with said ribs being of uniform cross section and extending lengthwise throughout the length of the workpiece member; thereafter reshaping a transversely extending portion of said workpiece member adjacent one end thereof to effect flattening and reshaping of end portions of said ribs to create on each said rib a downwardly sloped rib end part which closes off the end of the respective rib and which terminates in a flat edge flange which is generally coplanar with the base wall of the workpiece and extends transversely across the workpiece adjacent said one end thereof; said reshaping step including deforming the rib end portion downwardly toward the base wall to effect forming of (1) a sloped rib end wall which slopes downwardly from the rib top wall toward said base wall, and (2) a generally flat and horizontal wall part which projects longitudinally away from a lower end of the sloped rib end wall toward said one end of the workpiece and which defines part of said flat edge flange; and said reshaping step also including confining and reshaping the sidewalls of the rib end portion during the deforming thereof to provide a shape consistent with the shape of the rib and to minimize formation of wrinkles and surface irregularities; whereby channels of uniform cross section as defined between adjacent longitudinally extending ribs extend longitudinally continuously between adjacent deformed rib end portions so as to terminate at said flat flange. 